In a cutting processing using a rotation slot milling cutter, a processing of a slot shape is in a trend of gradually increasing, unlike existing slitting use, and when processing such a slot, a processing request quality after a slot processing gradually increases, and as a request of a radius form in a slot corner portion together increases, necessity of improvement of a structure of a cutting insert and a milling cutter appropriate thereto increases.
For reference, the slot milling is to process a concave portion of a concave form.
FIG. 1A is a perspective view illustrating an exemplary embodiment of a conventional rotation slot milling cutter, FIG. 1B is a detail view illustrating a portion A of FIG. 1A and illustrating an insert mounting seat structure, FIG. 1C is a perspective view of a conventional cutting insert, and FIG. 1D is a diagram illustrating a state of inserting and processing a cutting insert into a slot of a work material.
In general, in a rotation slot milling cutter 1, a plurality of cutting inserts 13 and 15 are provided in a circumference of a slot milling cutter body 11, as shown in the drawings, and one 13 (or 15) of every two cutting inserts 13 and 15 is protruded at one side surface of the milling cutter body 11, and the remaining one 15 (or 13) is protruded at an opposite side surface of the milling cutter body 11.
As shown in FIG. 1C, the conventional cutting inserts 13 and 15 have a structure in which a fastening through hole 13b is formed at the center thereof and in which a cutting edge 13a is formed at one side thereof along a circumference of a body portion of an approximately quadrangular hexahedron shape. An upper surface and a lower surface of the body portion are formed in a flat surface.
Further, a state of cutting a work material 30 using a conventional rotation slot milling cutter 1 is shown in FIGS. 2A and 2B, and FIGS. 2A and 2B illustrate a state in which an end portion of the slot milling cutter 1 is inserted into a slot of the work material 30.
Particularly, when a cutting edge of a thin width is formed in a radius R shape, a length of an edge portion is reduced by an R value, and thus a shape thereof is changed and distinguished according to a location that couples a cutting insert to both sides (the left side and the right side) of a milling cutter body.
Referring to FIG. 2A, when using the conventional rotation slot milling cutter 1, in a structure of a slot 20 formed in the work material 30, a surface of a front end portion 21 of a slot concave portion is not flat and forms an inclined shape. Therefore, in order to flatly form the front end portion 21 of a concave portion of the slot 20 formed in the work material 30, one surface of the cutting insert should have a surface of a bending shape.
Further, for a smooth slot milling processing, upon processing, a side surface of a cutting insert should form a predetermined allowance angle, and for a required width processing of a slot, it is necessary to prevent confusion of use according to a difference on a shape basis of a cutting insert coupled to a cutting insert mounting portion of both sides of a milling cutter body.
Particularly, in a conventional rotation slot milling cutter of FIG. 1B, as a means for coupling the cutting insert 13 (or 15) to the insert mounting seat 11a formed in one side of the milling cutter body 11, a seat protruded member 11b of a circular protrusion form is formed.
Therefore, the seat protruded member (11b of FIG. 1B) of a circular protrusion shape is inserted into the through hole 11d formed at the center of the cutting insert 13 (or 15) to be fastened by a separate fastening screw (not shown).
However, because the cutting insert 13 (or 15) fastened to an insert mounting seat 11a of the milling cutter 1 in which the circular seat protruded member 11b is formed has a commonly coupled structure regardless of a location of insert mounting seats 11a of both sides, the cutting insert may be erroneously mounted. Therefore, there is a problem that damage of a slot milling insert may occur due to part damage of the cutting insert and the slot milling cutter and there is inconvenience in using the slot milling insert.